The invention concerns a dog clutch between a drive mechanism of a cartridge holder and a ribbon drive of a ribbon cartridge of the type in which a spindle with dog components can be inserted in a clutch component for rotary drive of the clutch component.
Modern office machines use ribbon cartridges which contain the ribbon required for typing on a medium. The ribbon cartridges can be inserted in holders of the typewriters, with a drive mechanism arranged in this device being coupled with the ribbon drive in the ribbon cartridge through a dog clutch. To enable insertion of the ribbon cartridges in any position of the components to be coupled, the German Utility Model No. 82 23 076 suggests a formed spring serving as a drive pin and which engages entraining components of the ribbon drive only in expanded condition. But a rotary entrainment of the ribbon drive is effected only when the formed spring snaps into a corresponding recess of the entrainment component. Since an immediate drive of the ribbon is not ensured thereby, imprinting defects cannot be avoided.
Previously known from the German Utility Patent No. 81 13 901, moreover, is a dog clutch with a dog which is molded sideways to a spindle which can be inserted in the center of the clutch component. But this positive coupling has the disadvantage that drive elements of the drive mechanism can be damaged or destroyed if the ribbon locks inside the cartridge.
The problem underlying the invention is to provide a dog clutch which enables an insertion of the ribbon cartridges in the holder device in any position of the coupling parts, assures an immediate drive of the ribbon after installation of the cartridges, and reliably prevents drive elements of the drive mechanism from being destroyed or damaged in case of any locking of the ribbon.